Acoustic energy is increasingly utilized, directly or indirectly, in a large number of fields, including medical ultrasound diagnostic imaging, thermal bubble-jet inkjet personal printers, piezo-jet inkjet personal printers, non-destructive testing, sonar, and microphone technologies, to name a few. Distance sensors, mass-sensors, fluid-level sensors, and many security sensors also incorporate acoustic and ultrasonic devices. Emerging applications include the use of ultrasound to manipulate fluids or analyze samples on a microscopic scale within lab-on-a-chip devices. All of these involve the controlled application, passage or manipulation of acoustic waves created in a variety of manners.
Of substantial value would be the ability to switch, redirect or modulate the propagation of acoustic waves at low cost and on a fine scale amenable to micro-integration. This would allow reconfiguration of acoustic-based systems and components in a rapid dynamic manner on a grand scale, perhaps even in real time. This is not currently possible at low cost or on a fine scale. The acoustic waves we will manipulate are typically traveling in some sort of acoustic material or waveguide, such as in a gas-filled waveguide, liquid-filled waveguide, solid waveguide or in a substrate having technically useful acoustic or electroacoustic properties, such as lithium niobate. In any event, all such waves can be manipulated in accordance with the teachings of the invention in at least one of its embodiments. We also note that acoustic waves can take many forms such as bulk waves and surface waves of various well-known types, and the teachings of the present invention can be applied to one or more of these types separately or even simultaneously.
Likewise, RF (radio-frequency) energy and other high frequency electromagnetic waveforms are increasingly being employed in communications, radar, tracking devices, GPS (geopositioning systems), and in recent efforts to utilize terahertz electromagnetic energy to do medical diagnostic imaging and airport security screening. A similar means of inexpensively switching, modulating or redirecting such energies cheaply, and particularly on a fine scale, would be attractive. Potential applications include reconfigurable antennas, power-efficient personal communication devices, miniature security scanners, and self-healing electronic systems.
It would also be attractive to have a means of modulating electrical currents passing-through or potentials applied-to conductive-liquid microfluidic channels. Conductive liquids through which some electrical current flows, for example, are used in some continuous inkjet printers.
In these manners, one could implement networks or arrays of acoustic, electromagnetic or electrical-energy propagation switching, redirection and modulation devices using coplanar IC-style integration or other MEMs-like techniques in two- or three-dimensions. This would particularly have a large impact on what is possible in a consumer or mobile product. For RF devices, the present invention is seen as providing an additional tool with which to manipulate RF beyond existing FET switches and PIN diodes.
One prior art reference that we identified that may be relevant is “Switching Fiber-Optic Circuits with Microbubbles” by John Uebbing, appearing in Sensor Magazine in May 2003. In short, Uebbing utilizes thermally-formed microbubbles, such as the type employed in inkjet printing technology, to block or allow the propagation of light used in fiber-optic data lines-in the form of a bubble-based light switch. The bubbling-switch of their article is provided as a MEMS-based or micromachined bubble-array switch to compete with Texas Instruments DLMs™ or digital light mirrors, which are also useable as switch arrays for fiber-optic signals. Advantages are very high switching density at very low cost. As will be shown below, however, this reference is fundamentally different from our claimed invention.